In a medium bowl, whisk together flour, potato starch, baking powder and salt.

In a large mixing bowl, beat together butter and sugars until creamy and combined. Add egg and beat until combined, scraping down the bowl as needed. Mix in vanilla and almond extract.

Mix in 2 tablespoons of the sour cream until combined. Add half of the dry ingredients and mix just until combined. Mix in remaining sour cream, followed by the remaining flour. Divide dough in half and form each into a disc. Place each disc on a large piece of parchment paper and set another piece on top. Roll out each piece of dough until it is roughly 1/4" thick. Leave parchment paper on and transfer sheets into the refrigerator until the dough is firm, at least 30 minutes.

Meanwhile, preheat oven to 350 degrees.

Remove top sheets of parchment paper and cut out as many cookies as you can. Place cookies onto baking sheets lined with parchment paper. Bake until the cookies are just lightly browned around the edges, about 8 to 12 minutes. Remove from the oven and place sheet on a wire rack to cool for 5 minutes before transferring the cookies to a wire rack to cool completely.